Hello friends.
I had to drive down to Springfield this weekend, and I noticed
a vibration when I accelerated and set the cruise at about 65-
70. It's not noticable at lower speeds, and it seems to get
better if I accelerate to 80 or 85.
I was traveling on a rough road that was under construction
before I got on the Interstate, and I'm wondering if I knocked
one of my wheels out of alignment. My mechanic checked the
entire suspension and found no problems. He suggested having
the wheels spin balanced and aligned.
Specifically, the symptoms are:
*Upon accelerating to 65-70 mph, the gas pedal begins to vibrate.
*Noticable vibration on the floor below the pedals.
*" " in the driver's seat.
*" " in the steering wheel
I'm going to have the wheels balanced today. Do you all think
that's what the problem is? I took a trip last weekend and had
no such problems. Always something!! :)
Thanks for your comments.
-Michael.

Since it was okay before you got on the rough road, I suspect that you lost a wheel weight.

When you have the wheels balanced, MAKE SURE THEY DO A DYNAMIC BALANCE AND PUT WEIGHTS ON BOTH SIDES OF THE WHEEL!!!

I have had massive problems getting the tire stores to balance alloy wheels properly. They insist on putting the weights ONLY on the back of the wheel. This means that they are setting their machine to STATIC balance. This is the same as if you were using a bubble balancer, except you are putting ALL the weight on the back of the wheel which aggravates the dynamic balance.

Another problem you will often run into is that the tire store does not have the correct weight type for the wheels and the ones they use will easily be thrown off. There are two correct wheel weight types for your wheel. The generic one piece weight is a type EN. The best weight is a two piece weight that uses a clip. This is what Mercedes and their dealers use and it is the best way to go.

Failing the correct weight type, a good tire man can use tape weights on both planes by pushing the outer tape weight as far toward the outside as possible and still be on the inside diameter where centrifugal force will keep them in place. A "GOOD" tire man will have no trouble getting this done correctly. If you manage to find a "GOOD" tire man, make a note and tell your friends because they are few and far between.

I have suffered this frustration to a point that I finally bought my own wheel balancer so I could do the job correctly. My cars now have perfectly balanced wheels and are silk smooth to whatever speed I want to run.

I just called the shop that did my wheel alignment for me, and they said that they found problems with the front suspension and are preparing an estimate for me. I just had my MB mechanic check the suspension over, and he found no problems!!

I'm going to wait and see what they say is wrong, and how much it will cost. After doing some searching for others who have experienced suspension problems, I'm noticing that many of the problems are occurring between 125-160k. My car doesn't have 75k on it yet, and I find it hard to belive that there are suspension problems, other than the wheels being slightly out of balance.

It's impossible to troubleshoot something like this via a discussion group. It requires raising the car and prying and shaking everything.

Most things underneath that can wear out or break usually do not show themselves as a vibration. The exception, I suppose, could be extremely loose linkage along with an out of balance tire which sets up a harmonic vibration.

I had the same problem with my old 1992 2.6 190E....wheel balance was the problem and only the dealer could balance it correctly with the OEM weights...I had sportline' rims on it which were wider with the 205 sized tires which is still stock for the model. I too find it hard to beleive suspension on your car is wearing thin at 75K...also, maybe check the steering stabilizer shock...but really doubt its any more than the balancing of the wheels...let us know how you make out.

There are people out there BESIDES the dealer that are capable of balancing these wheels. The challenge is finding one of them. The two piece clip weights as used by MB are available through tire supply companies such as Myers and All Tire Supply. There is a special tool that is also available on the aftermarket. Failing the correct weights it can be done well with tape weights in the hands of someone who knows how to do it.

There is NOTHING magic about balancing these wheels if you have a halfway decent computer balancer and the proper attitude. In 20 minutes I could teach a high school kid how to do it properly. The challenge is finding someone who cares about doing it right.

Well I heard back from the shop today, and after doing a thorough check of the front suspension, they found that the idler arm was loose and that the wheel bearing had play. They are going to replace them for me. They also recommended that I get new tires, but I told them that I couldn't do that right now! Will wait until fall and will get some good tires put on before the winter.

Because they said that there was excessive play in both the arm and the bearings, I'm hoping that this will clear up the vibration that I'm getting.

I also posted this in the tire section, but I guess it wouldn't hurt to ask here: What is a GOOD all-around tire? Especially one that is known for good handling in snow? Is there such a tire??

Unfortunately...there aren't too many decent tire shops around the Hartford area and a few I've dealt with had no clue about the special weights used on MB wheels...not to mention they employed monkeys who had problems putting directional tires on correctly.

Though paying more at a dealer, unless you have a super indy; its your (at least my) best bet to have a dealer wrench stuff on the car...even to mount and balance a tire. I myself used to mount and dismount tires back in the day...its not hard like you say but some folks just don't give a crud when they do 50+ rims a day.